In general, the present invention concerns orthopedic implant systems for fixation of sacral area fractures and application in other skeletal areas. Most particularly, it concerns a system for fixation of the sacrum and/or sacroiliac joints, which can be applied ilium-to-ilium across the sacrum, and which employs a cannulated, locking screw that can be positioned in conjunction with tools including a guidewire through a minimally invasive, percutaneous surgical approach requiring only small incisions.
Various bone screws and other fasteners are well known in specific arts within the broad, general field of orthopedics, and use of such devices is widely accepted throughout the orthopedic community as a safe and effective treatment for patients having fractured bones. See, e.g., U.S. Pat. Nos. 4,013,071 which discloses fasteners particularly useful as orthopedic screws; 4,773,402 which discloses a dorsal transacral surgical implant; 5,129,901 which discloses a cannulated orthopedic screw; and 6,048,343 which discloses a bone screw system; plus Richards Manufacturing Co., Osteoporotic Bone Bolt with Nut-washer Combination, Jan. 26, 1972 product release; Zimmer, Inc., Threaded Bolts and Fixation Sets, February 1973 catalog REV-1, page A38; and Synthes catalog, Sacral Bar Kit, August 1984.
Cannulated bone screws, as such, have been produced for a number of years and made available in a variety of sizes to accommodate normal variations in patient anatomies. Compare, the ""343 patent to Mathis et al. The use of cannulated screws for hip fractures of the femur is also documented. Note, the ""901 patent to Decoste.
Further, the placement of screws in various aspects of the spine for immobilization, and supplemental fixation when performing spinal fusion procedures, has also become widely accepted over the last two decades. Compare, the ""402 patent to Asher et al.
Finally, the use of bolts having standard type machine screw threads, to which are mated washers and corresponding nuts, is known in various orthopedic applications. Compare, the Synthes Sacral Bar Kit. It is noted in particular, however useful it may be, that a technique of the type such as that which employs the Synthes kit is highly invasive, requiring large incisions, excision of significant portions of tissue, and employment of massive and unwieldy tools. Such significant and possibly not well tolerated intervention must be weighed seriously when a physician faces possible application of the same to an already traumatized patient who, perhaps among further damage, presents a fractured sacrum in need of fixation through emergency surgery.
It would be desirable to improve upon the foregoing. In particular, it would be desirable to provide for less invasive yet secure fixations of fractured sacra and/or sacroiliac joints through fixation with a fastener spanning iliac crests, notably in traumatized patients. Others have attempted yet failed to fulfill such desiderata.
The present invention provides, in one aspect, a screw system useful for transiliac fixation of a sacrum and/or a sacroiliac joint and/or for application in other skeletal areas, comprising:
a cannulated bone screw capable of spanning iliac crests of a patient, having an elongate, hollow body with openings on a first end of the body and on an opposing, second end of the body; a tip on the first end of the body, which, optionally but preferably, is a thread-cutting tip, which can engage and thread the ilia of the patient; a head about the second end of the body, which can be engaged with a surgical tool; and threads on at least part of the body between the first and second ends;
a locknut with threads for interference fitting corresponding generally to those of the screw for threading on the screw; and
optionally but preferably, a washer.
In other aspects, provided are the locknut itself; and a kit useful for transiliac fixation of a sacrum and/or a sacroiliac joint and/or for application in other skeletal areas, comprising:
at least one aforementioned screw system;
a guidewire, which is essentially as long as or longer than the elongate hollow body of the screw of the at least one screw system, and over which the screw can pass by the openings in the hollow body of the screw, and which, optionally but preferably, is rigid and has a drill bit tip; and
optionally but preferably, a cannulated starter drill and/or a tool set to engage the head of the screw for twisting the screw so that it can thread through bone and/or engage the nut so that it can be tightened onto the first end of the screw.
The invention is useful for repair of fractured sacra and fracture dislocations of the sacroiliac joint and/or in application(s) to other skeletal area(s).
Significantly, by the invention, problems in the art are ameliorated if not overcome. In particular, for example, the invention can be employed to repair a fractured sacrum through fixation of the sacrum with the screw spanning the iliac crests, and, what is most important, merely two, small percutaneous incisions are all that are normally required to implant the screw in the patient, who may be otherwise highly traumatized from the injury to his sacrum, if not elsewhere in his body. Accordingly, the invention is highly beneficial for the traumatized patient. Also, the cannulated, self-tapping screw with its locking nut is believed to be a first in the art, particularly with respect to sacral fixation. Beneficially, the system has metal-to-metal, major-minor, pitch-diamter locking interference fit fixation between the screw and locknut. This provides secure percutaneous fixation without significant risk for loosening.
Numerous further advantages attend the invention.